Electronic circuits often include a system for generating one or more known frequencies. These known frequencies are often related to clock signals. Clock signals may be generated using oscillator circuits and/or a frequency synthesizer. An oscillator circuit is typically capable of generating a single clock signal. But frequency synthesizers are typically capable of generating multiple clock signals using a single reference signal. The reference signal may be generated by an oscillator circuit. A typical frequency synthesizer circuit may utilize a phase-locked loop (PLL) circuit. PLL circuits include a feedback loop. The loop filter of the PLL occupies a relatively large area and the loop may suffer from stability issues with 2nd or higher order closed loops. In addition, analog blocks present in typical frequency synthesizer circuits, such as voltage controlled oscillators (VCO) and/or digitally controlled oscillators (DCO), may be sensitive to particular processes.